The Times-Picayune is marking the tricentennial of New Orleans with its ongoing 300 for 300 project, running through 2018 and highlighting the moments and people that connect and inspire us. Today, the series continues with New Orleans Gospel queen Mahalia Jackson's role in prompting one of the most famous speeches in American history.

THEN: Mahalia Jackson had been lifting up her voice for nearly her whole life, first as a singer at Mount Moriah Baptist Church in New Orleans, later as the music world's "Queen of Gospel" and then, in the 1960s, as an active player in the American civil rights movement. It was in that last capacity that she found herself on the dais for the historic Aug. 28, 1963, March on Washington. She was there to sing, which she did, performing the spirituals "How I Got Over" and "I Been 'Buked and I Been Scorned." But when she sat down, she wasn't quite done yet. As Martin Luther King Jr. began reading from his prepared remarks, she was inspired to lift up her voice once more. Sitting a few seats to his left, she shouted "Tell them about the dream, Martin!" At her prompting, King paused, pushed aside his prepared remarks and began speaking extemporaneously. Turns out, he had this dream ...

NOW: Jackson died at the age of 60 in 1972. New Orleans Mayor Moon Landrieu spoke at her funeral, which was held at the Rivergate, and her body was interred at Metairie's Providence Memorial Park. All these years later, her legacy is still strong in her hometown. Her name adorns the Mahalia Jackson Theater for the Performing Arts in Armstrong Park as well as a local elementary school. Even more notably, hers is remembered as one of the most powerful, and most important, voices ever to come out of New Orleans.

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Jackson and King were friends, having first met in Montgomery, Ala., during the bus boycott of 1955-'56. Often when he was having a rough day, it is said he would call her and ask her to sing to him over the telephone to lift his spirits.

After Jackson performed her two songs at the March on Washington -- and just before King took the stage -- CBS Newsman Roger Mudd reportedly said, "Mahalia Jackson. And all the speeches in the world couldn't have brought the response that just came from the hymns she sang. Miss Mahalia Jackson." He didn't know what was coming next.

The fact that King started by reading from prepared remarks was unusual for him. More often, he used a list of talking points that served as more of a loose blueprint for what he wanted to say and then improvised from there.

In a 2013 interview, former King speechwriter and adviser Clarence B. Jones remembered: "One of the world's greatest gospel singers shouting out to one of the world's greatest Baptist preachers. She may have ignored the fact that there were almost 300,000 other people there, and she just shouted out to Martin, 'Tell them about the dream.' Anybody else who would yell at him, he probably would've ignored it. He didn't ignore Mahalia Jackson. I said to somebody standing next to me, 'These people don't know it, but they're about ready to go to church.'"

It wasn't the first time King used the dream imagery. "All of a sudden this thing came to me that I have used -- I'd used many times before, that thing about 'I have a dream' -- and I just felt that I wanted to use it here," he said later, according to The New York Times.

Jackson grew up in the Black Pearl neighborhood of New Orleans. She dropped out of school in eighth grade to help support her family. Later, she harbored hopes of a career in nursing before discovering her ultimate calling.

N.O. DNA

In the decades since King's now-iconic speech echoed through the national mall in Washington, D.C., it has become recognized one of the most beloved and inspiring speeches in American history. While great progress has been made toward racial equality in America, there is still great work to be done -- but his dream is still alive, thanks in no small part to Mahalia Jackson and her singular ability to uplift and inspire.